Many types of ground-engaging tools are used in agriculture and the construction industry. Some tools (e.g., plows, harrows, brooms and the like) are carried by a vehicle (e.g., a tractor-drawn implement, self-propelled, etc.) and are adapted to be moved relative to the ground. However, it is sometimes desired to move a tool vertically relative to the ground, while being translated therealong, without any relative horizontal movement therebetween when the tool is in a lowered ground-engaging position.
Modern farming is a continuing struggle with economics. Various machines have been developed to reduce labor. However, these machines are often capital-intensive. On the other hand, the farmer who does not invest in such equipment often finds his operation to be unduly labor-intensive. Labor is not only expensive, but may simply not be available at critical times.
In recent years, increasing attention has been directed toward raised-bed mulch-covered farming. Such raised beds provide for improved drainage, and provide elevated seedbeds with defined aisles therebetween. The mulch is typically in the form of a much-elongated generally-rectangular sheet of plastic, and is used to cover the seedbed. Such mulch inhibits the growth of undesired weeds, and provides some control on evaporation. Both of these factors tend to increase the farmer's yield and reduce his costs.
Various techniques have been developed to use plastic mulch on raised seedbeds. According to one technique, the seedbed was prepared, planted, and was then physically covered with a sheet of imperforate plastic mulch. Thereafter, a laborer physically cut slits through the mulch at spaced locations therealong to allow for penetration of desired plant growth. While functionally operative, this technique was unnecessarily labor intensive.
Another known technique, such as the "E-Z Way Planter" manufactured by Renaldo's Sales & Service Center, Inc., 1770 Mile Strip Road, North Collins, N.Y. 14111, provided a tractor-drawn planter having a tool bar which was moved vertically upwardly and downwardly relative to the ground as the planter was moved along the seedbed. A gas-fired heated burner head was mounted on this tool bar to physically burn a hole in the mulch sheet when moved downwardly to engage it. A planter mechanism was adapted to inject an ideally-homogeneous mixture of seed and vermiculite through the just-burned hole. Thus, when the tool bar was lowered, the burner head melted a hole through the mulch, and the planter injected a plug of the seed-and-vermiculite mixture through the previously-burned hole. The tool bar was then moved upwardly, and, after being translated further along the seedbed, the burner head was again lowered to burn another hole, while the injector planted the mixture through the hole just burned. The planter mechanism was typically in the form of a rotatable ground-engaging "ferris wheel"-like device which was rotated so as to have a substantially-zero net horizontal velocity relative to the mulch sheet. On the other hand, the burner head was typically mounted for simple vertical movement relative to the horizontally-moving frame. Hence, the burner head had a continuous horizontal velocity component relative to the ground, even when it engaged the mulch. The consequence of this was that the burned holes were often elliptical, rather than circular, and, in some cases, the moving burner head actually tore or ripped the mulch.
Other types of ground-engaging tools are shown and described in U.S. Pat. Nos. 3,333,557 (Kappelmann et al.) [Class 111/Subclass 91 ], 3,460,493 (Stephenson et al.) [Class 111, Subclass 3], 3,945,330 (Leavitt et al. [Class 111/Subclass 1], 4,306,508 (Skipper) [Class 111, Subclass 1], 3,161,163 (Cosner et al.) [Class 111, Subclass 3], 4,458,608 (duBrucq) [Class 111, Subclass 3], and 3,176,635 (Mabson) [Class 111, Subclass 3].
Accordingly, it would be generally desirable to provide an improved through-the-mulch planter having an improved actuating mechanism which would selectively lower the tool bar to a ground-engaging position with substantially-zero net horizontal velocity relative to the seedbed so as to avoid damaging the mulch.